... but Tranquility on the sea in the marina. It reminded us of the Apollo 11 landings. The Mare Tranquilitatis was named in 1651 by two Jesuit priests who were early physicists. It escaped being a called the Mare Belgicum. It was an assumption by early astronomers that the dark flat areas on the surface of the Moon must be bodies of water like they would be on Earth but they are actually vast basaltic lava flows.